Project Summary/ Abstract Papillomavirus (PV) infections significantly impact human health. Mucosal PVs cause virtually all cases of human cervical cancer, while cutaneous PVs cause severe skin infections and non-melanoma skin cancers in patients with immunodeficiencies resulting from e.g. HIV infection, organ transplants, or genetic disorders. Treatments for cutaneous PVs are limited and often ineffective. Thus, there is a critical need for development of novel therapeutics directed at keratinocytes, the target cell of PV infections. Keratinocytes have the potential to mount an antiviral response. Viral infection activates interferon regulator factors (IRFs), which upregulate interferons (IFN) and IFN-stimulated antiviral genes. IRFs and IFNs are also tumor-suppressing, making them particularly attractive as therapeutic targets for PV infections. However, both mucosal and cutaneous PVs can repress IRF function and IFN expression. This repression is mediated by the E6 and E7 oncogenes of mucosal PVs. While limited studies suggest that mucosal and cutaneous PVs differ in their E6 and E7 functions and that IRF regulation of the IFN response in keratinocytes differs from that in other cell types, there are many more questions than answers. Like humans, cutaneous PV infections occur in dogs and are more prevalent in immunodeficient animals. Thus, the dog offers a natural spontaneous animal model for investigation of cutaneous PV infections and for testing novel therapeutics. Indeed, our preliminary data demonstrate that canine cutaneous PV E6 and E7 differentially disrupt IFN and IFN-stimulated gene expression in canine keratinocytes. The long-range goal of our work is to develop novel therapeutics targeting IRFs and the IFN response for treatment of cutaneous PV infections in immunodeficient patients, using a canine model of PV infection. We hypothesize here that E6 and E7 from cutaneous PVs enhance viral infection by inhibiting IRF function in keratinocytes using mechanisms unique to cutaneous PVs. In Aim 1, we will inhibit expression of IRFs to determine their impact on cutaneous PV infection and on constitutive and inducible expression of IFNs and IFN-stimulated genes in keratinocytes. In Aims 2 and 3, we will determine the mechanisms for cutaneous PV E6- and E7-mediated disruption of IFNs and IFN-stimulated gene expression in keratinocytes. Specifically, we will use mass spectrometry to identify E6 and E7 binding partners that modulate IRF expression and/or function, and then identify mechanisms for E6 and E7 effects on these binding partners. Using human PV and keratinocytes will address the human disease; using canine PV and keratinocytes will advance the dog model. Results will lay the foundation for development of novel therapeutics that would by-pass E6 and E7 deleterious effects. The mentoring team includes faculty with extensive expertise in keratinocyte biology, IRF and IFN biology in differentiated cells, PV biology, and mass spectrometry proteomics and bioinformatics. In sum, the proposed research will address a critical issue in human and animal health, capitalize on the diverse skill sets of the interdisciplinary mentoring team, and enhance my maturation as an independent clinician scientist.